81a1be14cb
`npx @google/design.md spec` failed with "Failed to load spec.md" in installed/published packages. The bundler emits the CLI to dist/index.js, so getSpecContent() resolves spec.md alongside it at dist/spec.md, but the build only copied docs/spec.md to dist/linter/. The dev-path fallback then resolves outside the package, so the command threw. Copy spec.md to dist/ as well, mirroring how spec-config.yaml is already copied to both dist/ and dist/linter/. Add a `spec` invocation to the tarball smoke test so the bundled-spec.md resolution is exercised in CI.